Knowledge of women's experience of childbirth in the outbreak of the coronavirus (COVID-19) pandemic and associated maternal health outcomes is scarce. A sample of primarily American women who gave birth around the height of COVID-19 (n = 1,611) and matched controls, i.e., women who gave birth before COVID-19 (n = 640), completed an anonymous Internet survey about recent childbirth, birth-related traumatic stress (peritraumatic distress inventory; PTSD-checklist), maternal bonding (maternal attachment inventory; mother-to-infant bonding scale) and breastfeeding status. Groups (n = 637 in each) were matched on demographics, prior mental health/trauma and childbirth factors to determine the unique contribution of COVID-19 to the psychological experience of childbirth. Mothers in COVID-19-exposed communities endorsed more clinically acute stress response to childbirth than matched controls (Z = 2.65, p = .008, OR= 1.38). A path mediation model revealed that acute stress mediated the relationship between study group and postpartum outcomes. Specifically, higher acute stress response in birth was associated with more childbirth-related posttraumatic stress disorder symptoms (β = .42, p < .001) and less bonding with the infant (β = .26, p < .001), including breastfeeding problems (β = .10, p < .01). Use of a convenient internet sample introduces bias towards more educated women and reliance on retrospective self-report assessments may entail recall bias. COVID-19 is a major stressor for delivering women. It can heighten traumatic childbirth experiences and interfere with successful postpartum adjustment. Clinical attention to traumatic stress in childbirth and problems with caring for the young during this pandemic is important. Copyright © 2020. Published by Elsevier B.V.